I make sure to keep a backup of my build as an image file incase my kids mess anything up.
I also disable the launch menu for the games in options run command.
And for mame I map the mame config menu to the keyboard as they don't use the keyboard.
And using kids mode.
I ended up making a seperate kids only setup and getting my kids a pi of their own and backed up their setup so if they do somehow manage to break it I can just rewrite the image.
They didn't want much content just some of their favourites and kodi